1. Field of the Invention
The present invention relates to a variable valve device and more specifically to a variable valve device used to change the lift degree of an intake valve in an engine.
2. Description of the Background Art
JP 2003-41976 A discloses a device that detects the operation angle of a control shaft in a variable valve mechanism (variable valve device) that continuously changes the valve lift degree and the valve operation angle of an intake valve in an internal combustion engine according to the operation angle (rotation angle) of the control shaft. The device includes an operation angle sensor (control shaft sensor) that generates an output according to the operation angle of the control shaft, so that an intake air amount is estimated based on the operation angle detected based on the output.
There is a certain relationship between the operation angle of the control shaft and the valve lift degree. However, the relationship changes when the variable valve mechanism is disassembled once and re-assembled, and the intake air amount cannot be estimated correctly in some cases. In such a case, the engine cannot be operated normally because the fuel injection amount, the fuel injection timing and the ignition timing cannot be controlled correctly based on the intake air amount.